Session KP01 - Poster Session III.
POSTER session, Tuesday afternoon, March 23
Exhibit Hall, GWCC
The unique features of NSTX, such as low aspect ratio, high plasma and energetic particle beta, low Alfvén velocity with the respect to beam ion injection velocity, and large Larmor radii present an entirely new regime for studying energetic particle physics, which need to be revisited. TAE stability is analyzed using the improved NOVA-K code, which includes finite orbit width and Larmor radiius effects and predicts the saturation amplitude for the mode using quasilinear theory. The analysis shows a broad spectrum of TAEs with different toroidal mode numbers. Most of eigenmodes are global because of strong toroidal coupling of the poloidal harmonics due to low aspect ratio. NBI ions are super Alfvénic producing a strong drive for TAEs. Trapped electron collisional damping is significant and can be shown to be of order \gamma / ømega \sim \beta_e for the ratio of the effective collisional frequency to the eigenfrequency to be \nu_\mathrmeff / ømega \simeq 0.1. ORBIT code is also used to study the effect of TAEs on beam ion confinement. It was found that the magnetic field well, which exists in high beta NSTX equilibria, provides a better confinement. Single TAE mode causes additional losses on the order of 5% for high beta case \beta_\mathrmav = 34 % and < 10% in low beta case \beta_\mathrmav = 10 %.